The world's power demands are expected to rise 60% by 2030. The International Energy Agency (IEA) estimates that fossil fuels, including oil and natural gas, will account for 85% of the energy market by 2030. Meanwhile, trillions of dollars worth of oil remain underground in apparently “tapped-out” wells. The present invention allows much of this domestic oil to be recovered, while generating clean, distributed electric power and reducing the amount of CO2 released into the atmosphere from combustion of natural gas. As both oil and clean electricity (CO2-emission-free electricity) represent products whose high value today will only increase in the future, the potential profit from the present invention is quite large.
The U.S. currently produces approximately 5.1 million barrels of oil a day. Most of the oil fields in the U.S. are declining in oil recovery productivity. It has been proven that using CO2 for Enhanced Oil Recovery (EOR) can increase oil recovery productivity in the declining fields. The U.S. Department of Energy (DOE) conducted several studies and has deemed CO2-EOR to be the most promising solution to increase oil recovery productivity. The DOE estimates that 100 million barrels of “stranded” oil can be recovered using CO2-EOR.
The DOE states that “while a mature hydrocarbon province, the U.S. still has 400 billion barrels of undeveloped technically recoverable oil resource. Undeveloped domestic oil resources still in the ground (in-place) total 1.1 Trillion barrels. Of this large in-place resource, 400 Billon barrels is estimated to be technically recoverable. This resource includes undiscovered oil, “stranded” light oil amenable to CO2-EOR technologies, unconventional oil (deep heavy oil and oil sands) and new petroleum concepts (residual oil in reservoir transition zones). The U.S. oil industry, as the leader in enhanced oil recovery technology, faces the challenge of further molding this technology towards economically producing these more costly remaining domestic oil resources. Of the 582 billion barrels of oil in-place in discovered fields, 208 billion has been already produced or proven, leaving behind 374 billion barrels. A significant portion of this 374 billion barrels is immobile or residual oil left behind (“stranded”) after application of conventional (primary/secondary) oil recovery technology. With appropriate enhanced oil recovery (EOR) technologies, 100 Billion barrels of this ‘stranded’ resource may become technically recoverable from already discovered fields.”
There are tens of thousands of depleted oil and natural gas wells around the world, which collectively possess significant amounts of petroleum resources that cannot currently be extracted using conventional extraction techniques. For example, in a typical oil well, only about 30% of the underground oil is recovered during initial drilling (“primary recovery”). An additional approximately 20% may be accessed by “secondary recovery” techniques such as water flooding. In recent years, “tertiary recovery” (also known as “Enhanced Oil Recovery,” or EOR) techniques have been developed to recover additional oil from depleted wells. Such tertiary recovery techniques include thermal recovery, chemical injection, and gas injection. Using current methods, these tertiary techniques allow for an additional 20% or more of the oil to be recovered.
Gas injection is one of the most common EOR techniques. In particular, carbon dioxide (CO2) injection into depleted oil wells has received considerable attention owing to its ability to mix with crude oil. Since the crude oil is miscible with CO2, injection of CO2 renders the oil substantially less viscous and more readily extractable.
Despite the potential advantages of CO2 in enhanced recovery, its use has been hampered by several factors. For instance, in order for the enhanced recovery process to be economically viable, the CO2 gas must be naturally available in copious supplies at reasonable cost at or near the site of the oil well. Alternatively, CO2 can be produced from industrial applications such as natural gas processing, fertilizer, ethanol and hydrogen plants where naturally occurring CO2 reservoirs are not available. The CO2 must then be transported over large distances via pipelines and injected at the well site. Unfortunately, such CO2 pipelines are difficult and costly to construct.
For most oil fields, a CO2 pipeline is not a viable option because of a mix of several problems: (a) The capital investment for building a pipeline—sometimes tens or hundreds of millions of dollars; (b) The time-frame of building a pipeline—several years; (c) The distance and terrain issues between the source and destination which either makes the pipeline impossible or simply not economical; (d) The time it takes to obtain easement rights and permits is long; and (e) The time it takes to start generating an increase in productivity—the return on investment (ROI) is too long.
For example, Anadarko Petroleum Corporation built a 125-mile CO2 pipeline in Wyoming from an ExxonMobil gas plant to Salt Creek, Wyo., a 100-year old oil field. They expect to increase production from approx. 5,000 bbl/day in 2005 to approx. 30,000 bbl/day by 2010. However, the project cost hundreds of millions of dollars, and took over 5 years of planning, permitting, and construction to complete. Therefore, when faced with the hurdles and overall costs of the pipeline-delivered CO2, as described above, tertiary CO2 EOR simply does not make economical sense for most oil fields, especially small and medium producers scattered all over the United States and the world.
In the past, the idea of using the exhaust from fossil-fuel fired electricity plants for EOR has been widely discussed. However, the electrical industry, for reasons of economy of scale, has based itself primarily on large (500 MW to 1 GW) central power stations, located near their primary metropolitan markets. For many reasons, including notably those laid out above, as well as the fact that flue gases from conventional fossil power plants typically contain relatively low (<10%) CO2 concentrations, such stations offer little potential utility for supporting EOR, especially by small producers.
Another gas that can potentially be used for enhanced recovery purposes is hydrogen. However, hydrogen has received considerably less attention than CO2. Hydrogen, although somewhat soluble with oil, is believed less so than CO2. Moreover, traditionally, hydrogen has been costly to produce and its use has not been justified from an economic standpoint.
The rising cost of crude oil, as high as $120 to $140 per barrel in the summer of 2008, and well over $70 per barrel in 2010 during the midst of a large economic recession, has increased interest in new enhanced oil recovery technologies. Simultaneously, the low cost of natural gas, often lower than $4/mcf, driven by the large number of natural gas discoveries as well as horizontal fracking of existing natural gas wells, has made natural gas an attractive fuel source for EOR.
Accordingly, as recognized by the present inventors, what are needed are a novel method, apparatus, and system for extracting oil from existing oil wells by utilizing CO2 driver gases generated from a natural gas source. What are also needed are a method, apparatus, and system for extracting natural gas from existing natural gas wells by utilizing CO2 driver gas generated from a natural gas source. As recognized by the present inventors, what is also needed is a natural gas steam reformer apparatus that is compact and portable.
Therefore, it would be an advancement in the state of the art to provide an apparatus, system, and method for generating large quantities of carbon dioxide, hydrogen and other gases from a natural gas source at low cost at or near an oil site. It would also be an advancement in the state of the art to provide a compact, portable natural gas steam reformer.
It is against this background that various embodiments of the present invention were developed.